The present invention is related to systems and methods for processing information, and more particularly to systems and methods for processing information received in a data transfer operation.
Data transfer systems typically include a receiver that converts an analog input into a stream of digital samples representing the analog input. For example, in a hard disk drive system, digital information is converted to an analog signal that is stored as a magnetic signal on a storage medium. The magnetic information is later sensed and converted back to an analog signal using a read circuit. The received analog signal is converted back to digital information representing the digital information originally provided to the storage medium. As another example, a wireless communication system involves a transmitter that receives digital information, and converts it to an analog signal that is transmitted. The analog signal is received and converted back to the original digital information that was originally prepared for transmission.
In such systems, the receiver typically utilizes a Viterbi algorithm data detector that is able to receive information including one or more errors, and to perform some level of error correction to reduce or eliminate any errors. Many approaches have been introduced to increase the achievable detector performance. For example, limited length pattern prediction filters looking only at previous bits on the media have been utilized. Such prediction filters have been tightly coupled to the final Viterbi detector target values, and operate as co-optimized filters that affect both the noise and expected portions of the received samples. Such approaches exhibit a variety of deficiencies including, but not limited to, an inability to consider the effect on a bit where a variety of different transitions may be involved, only a limited ability to de-correlate pattern dependent noise, and a length of data dependent detection that is fixed to the length of a final Viterbi target. Other approaches involve pattern dependent noise prediction to increase the bit error rate performance, but such implementations are typically highly complex. Further, the complexity of such approaches often causes a variety of difficulties in timing closure. To assure timing closure, such implementations are non-optimal and result in little if any increase in performance.
Hence, for at least the aforementioned reasons, there exists a need in the art for advanced systems and methods for processing received information.